from math import ceil

my_str = input()
# left = 0
# right = len(my_str) - 1
# while left < right:
#     if my_str[left] != my_str[right]:
#         print(f'{my_str}不是回文数')
#         break
#     left += 1
#     right -= 1
# else:
#     print(f'{my_str} 是回文数')

n = len(my_str)
half = ceil(n / 2)

if my_str[:half] == my_str[n:n - half - 1:-1]:
    print('yes')
else:
    print('no')
